Along with everything else advised here...try to always keep the tone of reviewing the code and not the coder. This can be very tricky..and you'll have to phrase what you say with some thought. Unless the programmer has had his/her code reviewed before and comes into the meeting understanding that this is about helping his/her code be better, s/he is likely to take everything you say as a personal attack. This chunk of code
is their creation and thus some programmers are very prideful of that and take great offense to anyone saying something bad about it.

Unless the other managers are also aware of this (and you may have to prep them), they can inadvertantly torpedo even your most carefully worded phrases.

For everything you find wrong, have a suggestion for how to improve it. Make the tone of the meeting be more like "we're offering our help to improve your skills and help you be a better programmer" instead of "Here's all the bad things you did, fix them and don't do it again".